Grizzly G9955 Dust Filter
I decided I needed to add dust control to my high speed rotary carving. Actually I decided that a long time ago. I have finally taken the first step. The Grizzly 9955 is about the cheapest version I could find as none of them do (that is filter) as well as I would like at a reasonable price.
I can’t fault this machine for that problem as it is the very nature of filtration that the smallest particles are the worse kind for human lung health and are also the hardest to filter out.
This filter says it will filter down to 5 microns but I have serious doubt of that, at least on a continuous basis. Most filters actually become more effective (not efficient) the dirtier they become (up to a point of no air flow or media failure) so where when is the 5 microns determined?
Yes, I am an air filtration expert from over 50 years in the HVAC business and having owned an air filtration service.
My propose here is to test the subjective effectiveness of this unit. I don’t have expensive test equipment to make critical measurements and I also don’t think in my case it is worth the effort to be that critical.
Note Grizzly on the label recommends (requires?) the use of the face mask filter when using the machine. So it is pretty clear the user should not depend on just this filter to provide safe breathing air.
I adjusted the poly carbonate panels to provide a narrow gap at the work area. This produces a higher velocity to the air flow at this point and better ensures the dust will be carried back to the filter material.
The filters are listed as 2 inch. That is a bit of a misleading statement but common in the filter business. The actual filter MEDIA material is about 1/4 to 3/8 inch thick and is pleated (folded) to the two inch thickness. This increases effective filter area, lowering velocity and providing better collection. It is the density of the media (or electrostatic attraction) that determines how fine a particle it will filter.
Fan noise is medium. The noise can easily be talked over and not loud enough to require ear protection.
The pictures show the dust collection on the left side of the filter material compared to the clean right side. I am right handed so most of the carving was done towards the left side. The brown dust visible on the filter was created only by the carving on the stick shown.
I could not detect any dust on the discharge of the fans (back side of box) at this time. I could slightly detect the odor of the oak dust in the air so there had to be some bypass (under 5 microns??). The garage door was open as shown.
My stage two plan is to provide a secondary closed system exhaust fan connected by 4 inch flex hose to the back of this box with the discharge air outdoors. This should eliminate all dust discharge into the working shop air.
Until then a face filter will be warn or the carving will be done with space fans clearing the shop air with the garage door open.